1. Field of the invention
The invention relates to the technical field of automatic identification of an imaging target, and more particularly to a method for identifying and positioning a building using mountain-based outline region restraint.
2. Description of the Related Art
Buildings in mountain areas are important parts of artificial buildings. For an infrared image having complex rolling hills as background, real-time detection and positioning of building targets is a key technique in navigation, and accurate positioning and identification thereof can meet requirement of unmanned aerial vehicles and manned aerial vehicles for applications such as accurate and automatic navigation, aircraft collision avoidance, and so on in the mountain areas.
If it is required that an aerial vehicle fly according to a predetermined route, a basic premise is that a route plan has to be made during flight preparation on the ground. However, errors in inertia navigation and positioning of the aerial vehicle may lead to route deviation in flying, and further direction deviation of an optical axis of an airborne imaging sensor. Therefore, a target image may not be located at the center of a view field, and may be to the left or right of the center, or above or below the center, which causes angular deviation between an actual target position and an estimated navigation position. Due to the existence of the deviation, it may be extremely difficult to guide the aerial vehicle to a predetermined target position by using an inertia navigation device only.
To correct the navigation deviation, it is possible to adopt forward-looking target identification of an optical sensor. However, conventional forward-looking target identification methods correct deviation between an actual flight route and a planned route by directly recognizing a target, which makes identification and positioning of a building impossible or unreliable in a case that optical imaging features of a target building is not salient (for example, the target building is hidden or shielded, the number of similar patterns of buildings is comparatively large, and local contrast of the building in optical imaging is poor). As the aerial vehicle approaches a building on a mountain from far away, since the building is in the vicinity of a mountain-based outline, false alarm may occur due to similar buildings on the same mountain, and full image searching may cause overhead of the method to be very high during direct identification of the building.